If the ECU detects an abnormal signal from a sensor while the vehicle is being driven, the ECU illuminates the engine trouble warning light and provides the engine with alternate operating instructions that are appropriate for the type of malfunction.
When an abnormal signal is received from a sensor, the ECU processes the specified values that are programmed for each sensor in order to provide the engine with alternate operating instructions that enable the engine to continue to operate or stop operating, depending on the conditions.
Self-Diagnostic Function table

Ecu self-diagnostic function
Troubleshooting methodShifting
Shifting
Shift pedal
Neutral position
Shifting gears lets you control the
amount of engine power available for
starting off, accelerating, climbing hills,
etc.
The gear positions are shown in the illustration.
TIP
To shift the transmission into the neutral
position, press the ...
Troubleshooting
Although Yamaha motorcycles receive
a thorough inspection before shipment
from the factory, trouble may occur during
operation. Any problem in the fuel,
compression, or ignition systems, for
example, can cause poor starting and
loss of power.
The following troubleshooting charts
repre ...
Coolant
The coolant level should be checked
before each ride. In addition, the coolant
must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
To check the coolant level
Place the vehicle on a level surface
and hold it in an upright position.
TIP
...